Rust inhibiting composition



Patented Jan. 12, 1954 RUST INHIBITING COMPOSITION John W. Bishop, Plainfield, N. J assignor to Tide Water Associated Oil Company, Bayonne, N. J., a corporation of Delaware No Drawing. Application May 26, 1950, Serial No. 164,627

15 Claims. 1

The present invention relates to novel compositions adapted for inhibiting corrosion and rusting of metal surfaces.

The compositions embodied herein find utility for many requirements wherein protection of normally corrodible metals against corrosion and rusting is desired but, in particular, they find utility as slushing compositions adapted for coating of metal articles, especially those of ferrous metals, for protection thereof against corrosionand rust-inducing atmospheres such as are often encountered during transportation, storage, etc., of such articles. In more specific illustration, the compositions embodied here find particular utility for application as a coating to metal surfaces of machined parts, engines, drums, piston rings, light arms, gears, etc., for protection thereof against corrosion and rusting upon exposure to adverse conditions for extended periods of time and which coatings may be read ily removed, such as by use of suitable solvents, from the metal surface if removal of the coating is desired prior to placing the metal article ency by applying to the surface of said metals a composition containing, as a rust inhibiting agent, a substituted ammonium salt formed by an acid ester of a phosphorus acid with an amine possessing an alkylol group that is esterified with a sulfonic acid. Such salts are described and claimed as novel compounds in my copending application, Serial No. 178,999, filed August 11, 1950. Generally speaking, the compositions embodied herein comprise a suitable substantially non-corrosive vehicle in major amount, based on the weight of the composition, and a minor amount, sufiicient to impart rust preventive characteristics to said composition, of a substituted ammonium salt as aforedefined, said compositions preferably being a solution of the salt in the vehicle, although in certain instances the compositions may be employed in the form of a dispersion. In specific embodiment, the compositions embodied herein comprise a suitable vehicle and substituted ammonium salt as afore said and, in addition, an acid ester of a phosphorus acid as, in many instances, use of the free acid ester in combination with the aforesaid substituted ammonium salts has been found to impart improved rust-protective characteristics to the compositions.

Although a wide variety of vehicles may be suitably employed in the compositions embodied herein, particularly preferred vehicles are hydrocarbons of the volatile and/or non-volatile type such as the non-drying substantially non-volatile type of oils derived from mineral oils and fractions thereof including lubricating oils, petrolatums, etc., mixtures thereof, and volatile substances of the aliphatic, aromatic or naphthenic type including substances such as hexane, petroleum ether, naphtha, other light petroleum derivatives, etc. In preferred embodiment, however, the compositions embodied herein comprise mineral oils of lubricating grade as the vehicle in combination with an oil-soluble rust inhibiting salt formed by an acid ester of a phosphorus acid with an alkylol-containing amine esterified with a sulfonic acid.

With reference to the phosphorus-containing acid ester component of the substituted ammonium salts, such acid esters may be broadly defined as esters of phosphorus acids that contain at least one acidic hydrogen, i. e., partially esterified phosphorus acids. For purposes of illustration, examples thereof include partially esterified compounds such as the monoand di-esters of phosphoric acid and mixtures of such esters. More specifically, the invention contemplates use of esters such as the aliphatic, alicyclicand arylcontaining acid esters of phosphoric acid and, still more specifically, acid esters of phosphorus acids that contain, as the residue of an esterifying alcohol, a hydrocarbon group containing a relatively largenumber of carbon atoms as, for example, from about four to about thirty carbon atoms and, more specifically, from about eight to about twenty carbon atoms. Illustrative of acid esters falling within the more preferred embodiments are the aliphatic acid esters such as may be illustrated by the 2-ethyl hexyl acid phosphates, octyl acid phosphates, lauryl acid phosphates, octadecyl acid phosphates, mixtures of such aliphatic acid esters, alicyclic acid esters such as the cyclohexyl acid phosphates, e. g., monocyclohexyl and dicyclohexyl acid phosphates, aryl and aliphatic-substituted aryl acid 3 esters such as the cardanyl acid phosphates, and the like.

The amines contemplated for esterification with a sulfonic acid, and for formation of the salts of the esterified amine with a phosphoruscontaining acid ester as aforedefined, may comprise a monoalkylol-containing-, a dialkylolcontaining-, and trialkylol-containing-amine, or mixtures thereof. Specific illustrations of such amines include trialkylol amines such as triethanol amine and tripropanol amine; alkyl alkylol amines such as ethyl diethanol amine, diethyl amino ethanol, di-butyl ethanol. amine, and butyl diethanol amine; cycloalkyl alkylol amines such as cyclohexyl diethanol amine, and aromatic-containing alkylol amines such as phenyl 'alkylol amines, and the like. Inpreferred embodiment the invention embodies use of tertiary alkyl alkylol amines such as the monoalkylol dialkyl amines and dialkylol alkyl amines,

specific illustrations of which are included in the examples set forth hereinafter. It should be understood, however, that although such specific illustrations have been set forth, the

invention is not limited to the use of such amines as in broad aspect the invention contemplates use of alkylol containing amines that'are esterifiable with a sulfonic acid for preparation of rust inhibiting substituted ammonium salts as aforedefined and adapted for use in combination with a noncor-rosive vehicle to provide rust inhibiting compositions as embodied herein.

The sulfonic acid component of the salts contemplated for use in practice of this invention may be derived from a wide variety of sulfonic acids including such acids derived from petroleum and known to the art as petroleum sulfonic acids as well as sulfonic acids synthetically Drepared by other means. Thus, for example, the sulfonic acid component embodied for use herein may be derived from sulfonic acids such as aliphatic-, aromatic-, or mixed aliphatic-aromatic-containing sulfonic acids, illustrative examples of which include lauryl, stearyl, benzyl and alkyl benzene sulfonic acids as well as poly sulfonic acids, an illustrative example of which is a polymeric polysulfonic acid having a molecular weight of about 3,300 and a neutralization equivalent of 390 and prepared from dodecyl benzene and acetaldehyde monosulfonic acid.

In further illustration, highly suitable sulfonic acids for use in practice of this invention are petroleum sulfonic acids known to the art as mahogany acids and generally formed when lubricating or similar petroleum fractions are treated with concentrated or fuming sulfuric acid. Such petroleum sulfonic acids are generally available in the form of their metal salts which are hydrolyzable to yield sulfonic acids suitable for use to esterify alkylol containing amines for production of esters useful for practice of this invention. Although, as aforesaid, a wide variety of sulfonic acids may be employed for esterification of the alkylol amines, particularly preferred are sulfonic acids having a relatively high molecular weight such, for example, as a molecular Weight of about 200 to about 600 illustrated by sulfonic acids of the mahogany acid type, or even higher molecular weight acids ,e. g., up to about 3,500 or more, such as the aforesaid polysulfonic acid prepared from dodecyl benzene and acetaldehyde monosulfonic acid.

" ring, the mixture along with heating thereof to elevated temperatures, e. g., about 200 F. On the other hand, the compositions embodied herein may also be prepared by preparing the acid phosphate salt of the esterified alkylol amine and adding the formed salt to the vehicle. Although the invention con-templates use of alkylol amines esterified with the .sulfonic acid for preparation of the salts thereof, irrespective of the method employed for such esterification of the alkylol amines, and no invention is claimed .in

preparation of the esterified alkylol amines, such esterification may illustratively be carried out by refluxing a mixture of the :sul-fonic acid and alkylol amine for about two to four hours with removal of excess or unreacted products'along with water formed by the esterification reaction. Thus, in the formation of esterified alkyl alkylol amines such as set forth in the following examples, esterification of the alkylol amines was carried out by refluxing a mixture of the sulfonic acid with the alkylol amine, using an amount of amine in excess of that theoretically required-to esterify the acid with subsequent removal of excess amine and water formed by the esterification. On the other hand and particularly when using amines such as the trialkylol amines, e. g., triethanol amine, the esterification is preferably carried out by using a reactant mixture comprising an amount of sulfonic acid substantially equivalent to that required to effect the desired degree of esterification of the amine in order to provide a reaction mixture devoid of or containing only a relativel low concentration of unreacted amine due to the difficulty of removing excess amine from the reaction mixture without resort to extensive means for removal thereof if the esterification is carried out using an excess of amine.

In order to further describe the invention, several examples are set forth hereinafter illustrating the markedly effective protection obtained against metal corrosion and rusting by practice of this invention. In the examples, determination of protective ability of the compositions was made by subjecting the compositions to the severe conditions of the humidity corrosion test .described in Army-Navy Aeronautical Specification Compound; Corrosive Pre- Sulfonic acids of the relatively high molecular weight type are preferred as they generally produce esters having improved solubility characventive, Aircraft Engine, AN-VV-C-576-B of April 2.8, .1945. Briefly, the test comprises coating two freshly sand blasted steel panels with the test composition, draining for four hours in an atmosphere maintained at a relative humidi ty not exceeding 50% and a temperature of 25 inducing conditions. At the end 'of the 'test period, the panels are removed from the humidity cabinet, cleaned with naphtha, and examined.

In the following illustrative examples and wherein reference is made to the use of a petroleum sulfonic acid in preparation of the rust inhibiting esters, the petroleum sulfonic acid was obtained by hydrolyzing (with hydrochloric acid) sodium salts of petroleum sulfonates marketed as Petronate and containing a concentration of about 60 to about 65% of the sodium salts of petroleum sulfonic acids in a mineral oil. The specific petroleum sulfonic acids, employed in the examples and used for esterifying the designated alkylol amines with formation of salts thereof and preparation of homogeneous solutions of the salts in a mineral oil, had a neutralization equivalent of 645/750 and an ash value of 2% by weight;

EXAMPLE I ing was obtained for a period of about 400 hours.

EXAMPLE II A composition was prepared comprising 97% by weight of a mineral lubricating oil and 3% of an additive comprising a substituted ammonium salt formed by lauryl acid phosphate with the esterified alkylol amine of Example I, using a reactant ratio of 1.2 moles of the acid phosphate to one mole of the esterified alkylol amine,

thus providing in the additive a slight excess of the acid phosphate over the amount theoretically required for forming the acid phosphate salt of the esterified alkylol amine. When subjected to the conditions of the aforesaid test, such a composition protected the metal panels against corrosion and rusting for a period of about 600 hours.

EXAMPLE III A composition was prepared comprising 97% by weight of a mineral lubricating oil and 3% of an additive formed by addition reaction of lauryl acid phosphate with an ester formed by partial esterification of triethanol amine by reaction thereof under esterifying conditions with a petroleum sulfonic acid as aforedefined, using a reactant ratio of one mole of triethanol amine to one mole of the sulfonic acid. In forming the acid phosphate salt of the esterified product, a ratio of 1.2 moles of the acid phosphate to one mole of the esterified alkylol amine was employed, thereby providing in the additive a slight excess of acid phosphate over that required to convert the esterified alkylol amine to the acid phosphate salts thereof. When subjected to the conditions of the aforesaid test, such a composition protected the metal panels against corrosion and rusting for a period of about 88 hours.

EXAMPLE IV A composition was prepared similar to that described in Example II except that diethyl amino ethanol was employed instead of the dibutyl amino ethanol. When subjected to the conditions of the aforesaid test, such a composition protected the metal panels against c01'-' period of about 500 rosion and rusting for a hours.

EXAMPLE V fonic acid. In formation of the salt, a ratio of 1.2 moles of the acid phosphate to one mole of the esterified alkylol amine was employed, thus providing in the additive a slight excess of the acid phosphate over that theoretically required to form the acid phosphate salts of the esterified alkylol amine. When subjected to the conditions of the aforesaid test, such a composition had protected the metal panels without evidence of corrosion and rusting upon observance after 750 hours of exposure.

As will be apparent to those skilled in the art, the use of the aforesaid salts of alkylolcontaining amines esterified with sulfonic acids provide highly effective protection of metals against rusting and corrosion upon exposure thereof to corrosion inducing conditions. Although, in the foregoing illustrative examples, specific concentrations of the salts have been employed, it should be understood that such concentrations have been used for illustrative purposes and are not intended as limiting the invention thereto. As will be further apparent to those skilled in the art, the concentration of salt employed may be varied over a rather wide range of concentrations depending upon factors such as the degree of corrosion prevention desired, solubility characteristics of the particular salt in the vehicle employed, etc. Generally, however, the salt is employed in amounts varying from about 0.01 to about 20% by weight of the composition, the lower concentrations generally being used for conditions that are not too severe towards enhancing metal corrosion and the higher concentrations for protection against more severe conditions. For most purposes, however, highly satisfactory results are obtained by use of about 0.5 to about 10% of the salt based on the weight of the composition.

Although, and as illustratively described in the foregoing examples, the compositions comprise a suitable vehicle and a salt as aforesaid, it is within the scope of this invention to include in the compositions embodied herein other addition agents for imparting certain desired properties to the compositions. In illustration, the compositions embodied herein may also contain substances such as anti-oxidants, pour point depressants, etc.

Although the present invention has been described in combination with certain preferred embodiments thereof, those skilled in the art will readily recognize that variations and modifications are to be considered within the purview of the specification and scope of the appended claims.

I claim:

1. A composition, adapted for inhibiting rusting of metals, comprising a mineral oil in major amount based on the weight of said composition and about 0.01 to about 20% based on the weight of said composition of a rust-inhibiting alkyl acid phosphate saltjof a tertiary alkylol-containingamine having an alkylol group esterified with a member from the group consisting of petroleum sulfonic acids and polymeric hydrocarbon sulfonic acids.

2. A composition, as defined in claim 1, wherein the acid phosphate component of the salt is lauryl acid phosphate and the alkylol-containing amine is a member from the group consisting of diethylaminoethanol, dibutylaminoethanol and triethanolamine.

3. A composition, adapted for use as a rustinhibiting coating for metals, comprising a substantially non-corrosive vehicle in major amount based on the weight of said composition, and a small amount, sufficient to impart rust-inhibiting characteristics to said composition, of a hydrocarbon acid phosphate salt of an alkylol containing amine having an alkylol group esterified with a hydrocarbon sulfonic acid.

4. A composition, as defined in claim 3, wherein the amine is a tertiary alkylalkylolamine.

5. A composition, as defined in claim 3, wherein the amine is a trialkylolamine.

6. A composition, as defined in claim 3, which, in addition, contains a small amount of a hydrocarbon acid phosphate. 7

7. A composition, as defined in claim 3, wherein the vehicle is a hydrocarbon.

8. A composition, as defined in claim 3, wherein the vehicle is a mineral oil.

9. A composition, as defined in claim 3, wherein the acid phosphate is an alkyl acid ester of phosphoric acid.

10. A composition, as defined in claim 3, whereamine.

, 11. A composition, as defined in claim 3, where-,

in the sulfonic acid is a petroleum sulfonic acid.

.12. A composition, adapted. for use as a rust-. inhibiting coating for metals, comprising a mineral oil in major amount based on the weight of said composition, and a small amount, sufiicient to impart rust-inhibiting characteristics to said composition, of an oil-soluble alkyl acid phosphate salt of a tertiary alkylol-containing amine having an alkylol group esterified with a hydrocarbon sulfonic acid.

13. A composition, as defined in claim 12, wherein the sulfonic acid is a petroleum sulfonic acid.

14. A composition, as defined in claim 12, wherein the alkyl group of the acid phosphate component of the salt contains about 4 to about 30 carbon atoms.

15. A composition, as defined in claim 14, wherein the alkyl group of the acid phosphate component contains about 8 to about 20 carbon atoms.

JOHN W. BISHOP.

References Cited in the file of this patent UNITED STATES PATENTS Number Name I Date 1,936,533 Albricht Nov. 21, 1933 2,233,001 Dickey Feb. 25, 1941 2,236,515 Cahn et a1. Apr. 1, 1941 2,313,573 Orthner Mar. 9, 1943 2,328,727 Langer Sept. 7, 1943 2,527,296 Bishop Oct. 24, 1950 

3. A COMPOSITION, ADAPTED FOR USE AS A RUSTINHIBITING COATING FOR METALS, COMPRISING A SUBSTANTIALLY NON-CORROSIVE VEHICLE IN MAJOR AMOUNT BASED ON THE WEIGHT OF SAID COMPOSITION, AND A SMALL AMOUNT, SUFFICIENT TO IMPART RUST-INHIBITING CHARACTERISTICS TO SAID COMPOSITION, OF A HYDROCARBON ACID PHOSPHATE SALT OF AN ALKYLOLCONTAINING AMINE HAVING AN ALKYLOL GROUP ESTERIFIED WITH A HYDROCARBON SULFONIC ACID. 